From nobody Sat Jul 25 07:27:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 357E5360EE8 for ; Tue, 14 Jul 2026 01:41:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993281; cv=none; b=pgc+SPJdqp9w4OmE/wNofKr3HUDhdSpDgtKhOpe9LEWkAKbtIIcqqEc275SG4MzXfiXuhWkXCiFKSZL3NSa6YdPD/tnrB+lhdbXNQS57IZf85eOxHsXuhueQlvfMEhcH0QY1LtOY/pDDvO3eUywYik7UtQPu85VHWPRCHejT0Po= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993281; c=relaxed/simple; bh=jME7UwAhFGdpy0DC+LD1XLRwwMwYlVOX++7xseGcuGo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eTQHE82lN5WDGoSnWLEqW5bmuA27nTJK7rgU4hxnBRGhN+FUQCZCV1+kUCq7OK9l56GA5gT0NVrXQ3d2cuRdm+FSPbLF7XCJEli4IuyR7X8A2zUSfT5hZy6biA6gO1/bfo9y4N2wozv9VfM4/naGvmTt7UhiyHSMW9RLNrlh42g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CsutLHcC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CsutLHcC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EACF1F00A3A; Tue, 14 Jul 2026 01:41:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783993280; bh=EYeyAMGYwgrEvRqPliDbY8/sG7cAJUpla97WO7oBIDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CsutLHcCRzlKNKj2DViWlid+pKZ5GBDxj6MKQlnzbJ/67UmuChIsHNZ4fC9Ia140L /vOZE4HbnKAVRAOfOK3265WJCwPy/MOT2Dxaem4aLRbL+FJLmBcKInrBp0QN8Uph0K xfRSOv4B11wLQ3ya2ZCAsK6+uPBzwY/BLd82cxd4Nm1Zig8/ntSz4TiQnvK0cyLHn8 Va6BOSpCvenuCs1FkRXlUnhjKzNXtFoE59BNoXJMgOiI3ccbL/YwK9/nUj0zTWYGcV L7HSZ4tABatpI0wX5okpWwqrLUWpegBO7KlD0G1jG/habGNLS0Zf2NYjZZHvxZSnPs pxFvYKpGieBzw== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang , Paolo Abeni Subject: [PATCH mptcp-next v4 1/7] mptcp: use local variable tp in sendmsg_frag Date: Tue, 14 Jul 2026 09:40:56 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang In mptcp_sendmsg_frag(), tcp_sk(ssk) is called multiple times. Introduce a local variable 'tp' to hold the tcp_sock pointer and use it throughout the function. This avoids repeated dereferencing and improves code readability, with no functional change. Suggested-by: Paolo Abeni Signed-off-by: Geliang Tang --- net/mptcp/protocol.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index ffcf5a1788f6..1cab07b1b9b1 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1375,6 +1375,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct= sock *ssk, u64 data_seq =3D dfrag->data_seq + info->sent; int offset =3D dfrag->offset + info->sent; struct mptcp_sock *msk =3D mptcp_sk(sk); + struct tcp_sock *tp =3D tcp_sk(ssk); bool zero_window_probe =3D false; struct mptcp_ext *mpext =3D NULL; bool can_coalesce =3D false; @@ -1410,14 +1411,14 @@ static int mptcp_sendmsg_frag(struct sock *sk, stru= ct sock *ssk, mpext =3D mptcp_get_ext(skb); if (!mptcp_skb_can_collapse_to(data_seq, skb, mpext)) { TCP_SKB_CB(skb)->eor =3D 1; - tcp_mark_push(tcp_sk(ssk), skb); + tcp_mark_push(tp, skb); goto alloc_skb; } =20 i =3D skb_shinfo(skb)->nr_frags; can_coalesce =3D skb_can_coalesce(skb, i, dfrag->page, offset); if (!can_coalesce && i >=3D READ_ONCE(net_hotdata.sysctl_max_skb_frags))= { - tcp_mark_push(tcp_sk(ssk), skb); + tcp_mark_push(tp, skb); goto alloc_skb; } =20 @@ -1471,7 +1472,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct= sock *ssk, skb->truesize +=3D copy; sk_wmem_queued_add(ssk, copy); sk_mem_charge(ssk, copy); - WRITE_ONCE(tcp_sk(ssk)->write_seq, tcp_sk(ssk)->write_seq + copy); + WRITE_ONCE(tp->write_seq, tp->write_seq + copy); TCP_SKB_CB(skb)->end_seq +=3D copy; tcp_skb_pcount_set(skb, 0); =20 --=20 2.53.0 From nobody Sat Jul 25 07:27:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91CF1360EE8 for ; Tue, 14 Jul 2026 01:41:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993282; cv=none; b=KCPIKTfW4hibQMYjo5+rpI+UI7n2Thm9aJZJNuXsnTQQMQgBD6c6m9LSWxLXxYi+JYKmezfcGz/udOx71ukPWFJMuA1/+KZi6AAXAh3KT/O6dCnkLJgUtr0nBe4jXLvnSjT+ChY592gxQn0wtpTp1KAJ4ccMmpZO2733oeXcH8U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993282; c=relaxed/simple; bh=kBi0yLOv/oI2k5sq55OaIAlOFS1OXgl4ObwpZc8E4uk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WMlCc56QoyBlavS6SuNyWr17TM3BX2kNFcDEtGm7S8Qf6mgDy/UQ7+il4O4LUeHpsvFtDx8K96SjzKltJ02IamLGT+52Yrnsq9D2giHT82rM/fVaHdR4R4U4r14qBjO/dgGMldSZO/S1/+Nx2tIBJshg6i+G00EhYn5musyHgh0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KwC9/uw6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KwC9/uw6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91FAA1F000E9; Tue, 14 Jul 2026 01:41:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783993281; bh=YupAB59tw+FVXwy+ZOzTZAeHm3llU1gWIUKkYa6d06c=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KwC9/uw6TadkaZRNiXJ3/wYN+yPu5VxkMIyU4DBb6rOtVJeSmOHke0A+W4I7f/yha 9PybQhtsA62ZsxnFLCJ8lew596zCjVB8+5yRpmw8f3hjnkH8i1OZjse5MJOzmCmIl3 tgEBGjHbNwZv/dw9dcUHC/p6gmNaqcCKk3/k3GIjoOK/Lrgk5ZnfY7K9jETsDf9Dp4 iWM4hdhx7uU7ULdGK7Y5eD7+P0PvWXvv3h38kNgVToqTIj8dz2+pMANLDhOIXTGU8u /pL0vMcXHRFYgPRXOvX6J8A082ZUs8M6B3+m9JvvVaT1JkNQpuBFxce3RCpSVQhNRh 4MZ4jX+TU4JXg== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v4 2/7] mptcp: remove redundant orig_offset in carve_data_frag Date: Tue, 14 Jul 2026 09:40:57 +0800 Message-ID: <457631a70151d3ee143f806dbe45e15ca9c0db16.1783992745.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang mptcp_carve_data_frag() already receives struct page_frag via its 'pfrag' parameter, making the separate 'orig_offset' parameter redundant since it merely duplicates pfrag->offset. Simplify the function signature by removing this unnecessary parameter and directly accessing the offset from struct pfrag internally. Signed-off-by: Geliang Tang --- net/mptcp/protocol.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 1cab07b1b9b1..111da68d5875 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1234,9 +1234,9 @@ static bool mptcp_page_frag_refill(struct sock *sk, s= truct page_frag *pfrag) } =20 static struct mptcp_data_frag * -mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfra= g, - int orig_offset) +mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfra= g) { + int orig_offset =3D pfrag->offset; int offset =3D ALIGN(orig_offset, sizeof(long)); struct mptcp_data_frag *dfrag; =20 @@ -2031,7 +2031,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msgh= dr *msg, size_t len) if (!mptcp_page_frag_refill(sk, pfrag)) goto wait_for_memory; =20 - dfrag =3D mptcp_carve_data_frag(msk, pfrag, pfrag->offset); + dfrag =3D mptcp_carve_data_frag(msk, pfrag); frag_truesize =3D dfrag->overhead; } =20 --=20 2.53.0 From nobody Sat Jul 25 07:27:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B84A363089 for ; Tue, 14 Jul 2026 01:41:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993284; cv=none; b=HV7N2vxCAIxVtYr6/DXVfRfFaCkU6m45HENTzpkNBVqMMp+6Mek2U+POITsFXECkBzRXlNsDaqa5cnGaKuEh7ICdYc5lLwtt5n6FvR5V9R3Amb6zU6mXdXx8JYfWW+5Fg+WOJTlI/OEZX91wSPq1uxI3UXv9lr9O1pGcTG2ATKQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993284; c=relaxed/simple; bh=H5Cm6cOKjRQ12zdvqcBfQ7flApDys2+Xoh65xEYrebg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VuFeC9v0UzPbj/2OERA3yGh2eWTDPA/49Ctqu9hyKxPwxIkdjxiudhGLXAHTfuTMMhRsDU39zXSOApCJPsOwJyPKzdNGi8fPl/RDpWPtE7db9e2Ls59TSL5uNPuzdqI8ykLdLwimofS59cb9uZzpFWG0LePPZ7BBZ7geyvdxqOc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=omrhoo1B; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="omrhoo1B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 071DA1F00A3A; Tue, 14 Jul 2026 01:41:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783993283; bh=LKBCAr8P8RPbgEXOZ6wTLjT24L/DmR9qQDfKSvOV2Dg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=omrhoo1BH+MDYLWCYJ06qlP+52K4GuvBhs1OVtS5hR2GaKXmLQfw1SpYuas3O4MtH dugidtjziGmf2ysgyZrgBzrpaFeSNvFZWWD/AUHJe2K61gDPKnKoOPNhHSCKZckcCS 1RonYkex9cXd6IfFckKju6cnjdNsTO9YjrYTa6ej+isesB2bBg6S6lFEXEL6bJua8N vCPpZCe1C3rGhf/Q59NZND3v+IKkPhm39zfiN2tXts9EhPRn8LFpjtGQLYIR+osux2 m2WzwRECFsULK3WqnBiz+3BSKuFMv1E9Qe/SQ7ctzBOfZTDnbzjc4ZlQ+yldYUZZjh t8NRt1DtTDsRg== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v4 3/7] mptcp: add MSG_ZEROCOPY support Date: Tue, 14 Jul 2026 09:40:58 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang This patch enables MSG_ZEROCOPY support for MPTCP sockets, allowing user-space to transmit data without intermediate kernel copies. The implementation follows the same lifecycle model as TCP: A single ubuf_info_msgzc is allocated per sendmsg via msg_zerocopy_realloc(). Its reference count consists of three parts: one 'caller' reference held until sendmsg returns, one reference per MPTCP dfrag in the retransmission queue (released when the dfrag is acked and cleared), and one reference per subflow skb that consumes dfrag bytes (released by TCP's skb_zcopy_clear() when the skb is acked). Completion is reported only after all bytes are acknowledged at both MPTCP and subflow levels. User pages are pinned via iov_iter_get_pages2() and stored directly in a newly allocated mptcp_data_frag. The dfrag takes one reference on the ubuf_info and one on the page. Subflow skbs take additional page references via get_page() and are marked with skb_zcopy_set() and SKBFL_PURE_ZEROCOPY, mirroring TCP's behavior and bypassing kernel memory accounting for those pages. The feature is silently downgraded to regular copy when MSG_FASTOPEN is set or the application has not opted in via setsockopt(SO_ZEROCOPY). If msg_zerocopy_realloc() fails (e.g. RLIMIT_MEMLOCK pressure), sendmsg(2) aborts with -ENOBUFS. Signed-off-by: Geliang Tang --- net/mptcp/protocol.c | 107 ++++++++++++++++++++++++++++++++++++++++--- net/mptcp/protocol.h | 1 + 2 files changed, 101 insertions(+), 7 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 111da68d5875..d40fc5a89309 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1118,9 +1118,11 @@ static bool mptcp_frag_can_collapse_to(const struct = mptcp_sock *msk, df->data_seq + df->data_len =3D=3D msk->write_seq; } =20 -static void dfrag_uncharge(struct sock *sk, int len) +static void dfrag_uncharge(struct sock *sk, int len, + struct mptcp_data_frag *dfrag) { - sk_mem_uncharge(sk, len); + if (!dfrag->ubuf) + sk_mem_uncharge(sk, len); sk_wmem_queued_add(sk, -len); } =20 @@ -1129,7 +1131,13 @@ static void dfrag_clear(struct sock *sk, struct mptc= p_data_frag *dfrag) int len =3D dfrag->data_len + dfrag->overhead; =20 list_del(&dfrag->list); - dfrag_uncharge(sk, len); + dfrag_uncharge(sk, len, dfrag); + if (dfrag->ubuf) { + net_zcopy_put(dfrag->ubuf); + put_page(dfrag->page); + kfree(dfrag); + return; + } put_page(dfrag->page); } =20 @@ -1174,7 +1182,7 @@ static void __mptcp_clean_una(struct sock *sk) dfrag->data_len -=3D delta; dfrag->already_sent -=3D delta; =20 - dfrag_uncharge(sk, delta); + dfrag_uncharge(sk, delta, dfrag); } =20 /* all retransmitted data acked, recovery completed */ @@ -1248,6 +1256,7 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, s= truct page_frag *pfrag) dfrag->already_sent =3D 0; dfrag->page =3D pfrag->page; dfrag->eor =3D 0; + dfrag->ubuf =3D NULL; =20 return dfrag; } @@ -1417,6 +1426,11 @@ static int mptcp_sendmsg_frag(struct sock *sk, struc= t sock *ssk, =20 i =3D skb_shinfo(skb)->nr_frags; can_coalesce =3D skb_can_coalesce(skb, i, dfrag->page, offset); + if (skb_zcopy_pure(skb) !=3D !!dfrag->ubuf) { + can_coalesce =3D false; + tcp_mark_push(tp, skb); + goto alloc_skb; + } if (!can_coalesce && i >=3D READ_ONCE(net_hotdata.sysctl_max_skb_frags))= { tcp_mark_push(tp, skb); goto alloc_skb; @@ -1455,7 +1469,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct= sock *ssk, } =20 copy =3D min_t(size_t, copy, info->limit - info->sent); - if (!sk_wmem_schedule(ssk, copy)) { + if (!dfrag->ubuf && !sk_wmem_schedule(ssk, copy)) { tcp_remove_empty_skb(ssk); return -ENOMEM; } @@ -1465,13 +1479,19 @@ static int mptcp_sendmsg_frag(struct sock *sk, stru= ct sock *ssk, } else { get_page(dfrag->page); skb_fill_page_desc(skb, i, dfrag->page, offset, copy); + + if (dfrag->ubuf && !skb_zcopy(skb)) { + skb_zcopy_set(skb, dfrag->ubuf, NULL); + skb_shinfo(skb)->flags |=3D SKBFL_PURE_ZEROCOPY; + } } =20 skb->len +=3D copy; skb->data_len +=3D copy; skb->truesize +=3D copy; sk_wmem_queued_add(ssk, copy); - sk_mem_charge(ssk, copy); + if (!skb_zcopy_pure(skb)) + sk_mem_charge(ssk, copy); WRITE_ONCE(tp->write_seq, tp->write_seq + copy); TCP_SKB_CB(skb)->end_seq +=3D copy; tcp_skb_pcount_set(skb, 0); @@ -1968,22 +1988,80 @@ static void mptcp_rps_record_subflows(const struct = mptcp_sock *msk) } } =20 +static int mptcp_sendmsg_zerocopy_iter(struct sock *sk, struct msghdr *msg, + struct ubuf_info *ubuf, u32 copy_limit, + ssize_t *copied, long *timeo) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + struct mptcp_data_frag *dfrag; + struct page *pages[1] =3D {}; + size_t pg_off =3D 0; + ssize_t pg_len; + + pg_len =3D iov_iter_get_pages2(&msg->msg_iter, pages, + copy_limit, 1, &pg_off); + if (pg_len < 0) + return pg_len; + /* pg_len =3D=3D 0 means the iterator is exhausted */ + if (pg_len =3D=3D 0) + return -EAGAIN; + + dfrag =3D kzalloc_obj(*dfrag, GFP_KERNEL_ACCOUNT); + if (!dfrag) { + iov_iter_revert(&msg->msg_iter, pg_len); + put_page(pages[0]); + return -ENOMEM; + } + dfrag->data_len =3D pg_len; + dfrag->data_seq =3D msk->write_seq; + dfrag->offset =3D pg_off; + dfrag->page =3D pages[0]; + dfrag->ubuf =3D ubuf; + + /* one ref for the dfrag; released in dfrag_clear */ + net_zcopy_get(ubuf); + + *copied +=3D pg_len; + WRITE_ONCE(msk->write_seq, msk->write_seq + pg_len); + sk_wmem_queued_add(sk, pg_len); + + list_add_tail(&dfrag->list, &msk->rtx_queue); + if (!msk->first_pending) + msk->first_pending =3D dfrag; + + return 0; +} + static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) { struct mptcp_sock *msk =3D mptcp_sk(sk); + struct ubuf_info *ubuf =3D NULL; struct page_frag *pfrag; size_t copied =3D 0; + bool zc =3D false; int ret =3D 0; long timeo; =20 /* silently ignore everything else */ msg->msg_flags &=3D MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | - MSG_FASTOPEN | MSG_EOR; + MSG_FASTOPEN | MSG_EOR | MSG_ZEROCOPY; =20 lock_sock(sk); =20 mptcp_rps_record_subflows(msk); =20 + if (msg->msg_flags & MSG_FASTOPEN || !sock_flag(sk, SOCK_ZEROCOPY)) + msg->msg_flags &=3D ~MSG_ZEROCOPY; + + if ((msg->msg_flags & MSG_ZEROCOPY) && len) { + ubuf =3D msg_zerocopy_realloc(sk, len, NULL, false); + if (!ubuf) { + ret =3D -ENOBUFS; + goto do_error; + } + zc =3D true; + } + if (unlikely(inet_test_bit(DEFER_CONNECT, sk) || msg->msg_flags & MSG_FASTOPEN)) { int copied_syn =3D 0; @@ -2022,6 +2100,15 @@ static int mptcp_sendmsg(struct sock *sk, struct msg= hdr *msg, size_t len) if (!copy_limit) goto wait_for_memory; =20 + if (zc) { + ret =3D mptcp_sendmsg_zerocopy_iter(sk, msg, + ubuf, copy_limit, + &copied, &timeo); + if (ret) + goto do_error; + continue; + } + /* reuse tail pfrag, if possible, or carve a new one from the * page allocator */ @@ -2097,6 +2184,8 @@ static int mptcp_sendmsg(struct sock *sk, struct msgh= dr *msg, size_t len) } =20 out: + if (zc) + net_zcopy_put(ubuf); release_sock(sk); return copied; =20 @@ -2105,6 +2194,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msg= hdr *msg, size_t len) goto out; =20 copied =3D sk_stream_error(sk, msg->msg_flags, ret); + if (zc) { + net_zcopy_put_abort(ubuf, true); + zc =3D false; + } goto out; } =20 diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index da40c6f3705f..f4e69ea51a94 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -268,6 +268,7 @@ struct mptcp_data_frag { u8 eor; /* currently using 1 bit */ u16 already_sent; struct page *page; + struct ubuf_info *ubuf; }; =20 /* Arbitrary compromise between as low as possible to react timely to subf= low --=20 2.53.0 From nobody Sat Jul 25 07:27:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BCFE6360EE8 for ; Tue, 14 Jul 2026 01:41:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993285; cv=none; b=pywt0qVyI1N7mkz7b8EyrjRBqKgPPwH8QxcZc5bOJh3eU2haI6GeJfiGffxSRKXKoQt8bnmRq4J0x/3L5dQ/vc8Drxuroo9SaoGD253C8IIcF7bhU6bTdxoQXnJIr9j+O6Vp7obQr0bcgC2x8X+4CD39kZ3bxVTs6UXmiUwzxtI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993285; c=relaxed/simple; bh=h0KHbTdRLXfAQDlm+Mzn4sOSwJyxsp1fPSLu/6K0DEU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=l+Qyj9VExt6ssn5jv49GI2YVJbxXE1sjSLIACOnj8cCY77OPMV6EIRjiCDyt1IyKgoe4S7y6GNjkc3PL5wRH53lYPd10WSfpDE7xAIL12vzUgksi8munY3tfZ6Hexs49qeuXp4O6kuXd34oKzGh08lFX0VSqemdNHc9EjH+y57M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iKeHhBu1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iKeHhBu1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96E3D1F000E9; Tue, 14 Jul 2026 01:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783993284; bh=1aL2W8PM3bCKMiZfqkj5j62ROsq0aloJ4VBeqLorDFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iKeHhBu1CX5yA0mFdpEeKHQe3We4uMd0GhjeA0pvYJfcaNXD+SCDcO3ft7OUF2M5f Rau1Kq3/RDcIkKLwBmsDPtshWD6h/pEfQ9r6JVfvq+TLq6+9CjbCRowIv5+D0S0pLM EtiYBVZ9tNtvMQZ4T/vI0ydForTdD42/mbA5UsUj6o1y5QOfoPPXrNdryryB0dQAl5 3kNMmWdHLQcES0YKcQvkQmwmcJjiszQ7VryGQG4qxLSzXJwiWw18jrr5aZooEn/gzL KM9dS7IyJImZGiJ3d+xQk5tVz6GmjX8r00KmQvc6P73fNt5AdPEscXnEUp4v/Im4z+ +ZnIgBUlzUqdQ== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v4 4/7] mptcp: handle SO_ZEROCOPY in setsockopt Date: Tue, 14 Jul 2026 09:40:59 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang SO_ZEROCOPY is currently rejected by MPTCP setsockopt with -EOPNOTSUPP, even though the matching MSG_ZEROCOPY path in mptcp_sendmsg() is wired up. As a result MSG_ZEROCOPY silently falls back to a copy on MPTCP sockets because the opt-in flag is never set. Expose SO_ZEROCOPY through the SOL_SOCKET setsockopt dispatcher. The new mptcp_setsockopt_sol_socket_zerocopy() helper validates that val is 0 or 1 (matching standard TCP sk_setsockopt) and flips SOCK_ZEROCOPY on the msk only. mptcp_sendmsg() consults the same flag directly, so opt-in is honoured on every data path without any cross-socket propagation. Signed-off-by: Geliang Tang --- net/mptcp/sockopt.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index fcf6feb2a9eb..abcc7d4452b4 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -175,6 +175,19 @@ static int mptcp_setsockopt_sol_socket_tstamp(struct m= ptcp_sock *msk, int optnam return 0; } =20 +static int mptcp_setsockopt_sol_socket_zerocopy(struct mptcp_sock *msk, in= t val) +{ + struct sock *sk =3D (struct sock *)msk; + + if (val !=3D 0 && val !=3D 1) + return -EINVAL; + + lock_sock(sk); + sock_valbool_flag(sk, SOCK_ZEROCOPY, val); + release_sock(sk); + return 0; +} + static int mptcp_setsockopt_sol_socket_int(struct mptcp_sock *msk, int opt= name, sockptr_t optval, unsigned int optlen) @@ -203,6 +216,8 @@ static int mptcp_setsockopt_sol_socket_int(struct mptcp= _sock *msk, int optname, case SO_TIMESTAMPNS_OLD: case SO_TIMESTAMPNS_NEW: return mptcp_setsockopt_sol_socket_tstamp(msk, optname, val); + case SO_ZEROCOPY: + return mptcp_setsockopt_sol_socket_zerocopy(msk, val); } =20 return -ENOPROTOOPT; @@ -342,6 +357,7 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_soc= k *msk, int optname, case SO_TIMESTAMP_NEW: case SO_TIMESTAMPNS_OLD: case SO_TIMESTAMPNS_NEW: + case SO_ZEROCOPY: return mptcp_setsockopt_sol_socket_int(msk, optname, optval, optlen); case SO_TIMESTAMPING_OLD: @@ -387,7 +403,6 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_soc= k *msk, int optname, * SO_CNX_ADVICE is currently unsupported, could possibly be relevant, * but likely needs careful design * - * SO_ZEROCOPY is currently unsupported, TODO in sndmsg * SO_TXTIME is currently unsupported */ =20 --=20 2.53.0 From nobody Sat Jul 25 07:27:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2B9A304972 for ; Tue, 14 Jul 2026 01:41:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993287; cv=none; b=mbtx5gPmg70uhiJYjIUGN3OkyfcGAmHfPvmILzHB+mqdBcLohjhrBGBfjbou3rLh9h49MERoHc16vQ09T8DpiKnl8v5Yt3IhNxI/hVwybM4RQDr94bsg2mPqPeRp4UywOHLxSgBxCrqVKUTR7gEycI2g4iy+j+xHwuJ8HaDkM0Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783993287; c=relaxed/simple; bh=+5gECfAasnY7FjAd33wleEiN68JRNA7MFYQTlVrn6e0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qNo6Q7ZiJf6A/i1AcSGJEm0MtH//dDOtIQ3nvrjrZu+uXEB62L0/k7XnVbh4W2DkYtnJLztv/66ILKcN1qqDbk4Lem+aLt7d+PT9vOQTRPWGklka3YczVs+PVt0dvPym4aaS6CdBvm32zXAXraGWeko7T61YXg4BE2qRxNq1SW4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=evRlXHYw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="evRlXHYw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18E5A1F00A3A; Tue, 14 Jul 2026 01:41:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783993286; bh=hLr/ccAJbC9rJxh6YAwf4gmARJvi2ew9pa3yx7p+AoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=evRlXHYwA9GYZRG1Cjx8k4SYbK1iIZXJ3FHn8Hmp8wat4rsvBzyBlroxft2ps1Grq V84qYU7FJ81x2v75UGDiw8XrCrKvGaa90ZiSgtAXh64UrftnpZXXvKqVIwknhcWcvp n5RdKFV2ywyXvLLtGe+EWvWK7zU99atYfj/7y12kmps3DbyJDkP6IJrikel0FdI6ga ibR6EBi5YzLcpW0iCAyF8UCLogw0bzrzMxjHlKVJQjD+utXYgrcZ36r2wh0Y4fM72d xY7sLSv7EaOnobcuiKPzuKKFX6PPkoJJblNef8qYu1zBXr2D9VCSwM3JeU1Ku3c0lH UE48b4qX3jvGw== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v4 5/7] selftests: mptcp: connect: add zerocopy io mode Date: Tue, 14 Jul 2026 09:41:00 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang Add a new I/O mode 'zerocopy' to the mptcp_connect selftest, which uses sendmsg() with the MSG_ZEROCOPY flag to transmit data. This enables testing and performance validation of the zero-copy send path for both TCP and MPTCP connections. This mode is useful for benchmarking and for verifying correctness of MSG_ZEROCOPY handling in the MPTCP stack. Signed-off-by: Geliang Tang --- .../selftests/net/mptcp/mptcp_connect.c | 121 +++++++++++++++++- 1 file changed, 120 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/test= ing/selftests/net/mptcp/mptcp_connect.c index ea4cb6c1bd5e..4a941a780620 100644 --- a/tools/testing/selftests/net/mptcp/mptcp_connect.c +++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c @@ -33,6 +33,7 @@ #include #include #include +#include #include =20 extern int optind; @@ -53,6 +54,7 @@ enum cfg_mode { CFG_MODE_MMAP, CFG_MODE_SENDFILE, CFG_MODE_SPLICE, + CFG_MODE_ZEROCOPY, }; =20 enum cfg_peek { @@ -125,7 +127,7 @@ static void die_usage(void) fprintf(stderr, "\t-j -- add additional sleep at connection start and= tear down " "-- for MPJ tests\n"); fprintf(stderr, "\t-l -- listens mode, accepts incoming connection\n"= ); - fprintf(stderr, "\t-m [poll|mmap|sendfile|splice] -- use poll(default)/mm= ap+write/sendfile/splice\n"); + fprintf(stderr, "\t-m [poll|mmap|sendfile|splice|zerocopy] -- use poll(de= fault)/mmap+write/sendfile/splice/zerocopy\n"); fprintf(stderr, "\t-M mark -- set socket packet mark\n"); fprintf(stderr, "\t-o option -- test sockopt